1. Field of the Invention
This invention relates to backing up data, and more particularly to apparatus and methods for using the change-recording feature of point-in-time-copy technology to perform more effective backups.
2. Background of the Invention
Data is increasingly one of an organization's most valuable assets. Accordingly, it is paramount that an organization regularly back up its data, particularly its business-critical data. Statistics show that a large percentage of organizations are unable to recover from an event of significant data loss, regardless of whether the loss is the result of a virus, data corruption, physical disaster, software or hardware failure, human error, or the like. At the very least, significant data loss can result in lost income, missed business opportunities, and/or substantial legal liability. Accordingly, it is important that an organization implement adequate backup policies and procedures to prevent such losses from occurring.
Currently, various products (i.e., applications) may be used to back up data residing on enterprise storage systems, such as IBM's DS8000 enterprise storage system or other analogous or comparable storage systems. Such backup products may perform a full backup followed by incremental backups that contain data that has changed since the initial full backup or prior incremental backup. The advantage of performing incremental backups as opposed to full backups is that they are generally faster and consume less storage space than multiple full backups.
In order to perform incremental backups, some of the above-mentioned backup products read metadata such as the Volume Table of Contents (hereinafter “VTOC”) or the VSAM catalog (hereinafter “catalog”) to determine what data has changed since a previous backup. A VTOC, in particular, may include an indicator for each data set indicating whether the data set has been modified since the last backup. Backup products may use this indicator to determine if a data set should be included in an incremental backup.
Unfortunately, the indicators in VTOCs and catalogs are often unreliable since they may be updated even if the associated data sets have not been modified or have been modified in an insignificant way. For example, these indicators may be set if a data set has been opened or referenced in a way that does not change the underlying data. These indicators may also be set if a small or insignificant amount of data in a data set has been changed. This may cause a backup product to back up an entire data set even if the data set has not changed or has changed insignificantly.
In view of the foregoing, what are needed are apparatus and methods to more reliably and effectively back up data sets stored in enterprise storage systems or other storage devices.